The oldest stars are planet killers, according to a new study that reveals a shocking truth about the fate of planets orbiting close to their stars. As stars age, they expand, and this expansion spells doom for the planets closest to them. The study, published in the Monthly Notices of the Royal Astronomical Society, suggests that planets orbiting their stars in just 12 days or less are at a higher risk of being destroyed by their aging suns. But here's where it gets controversial... The idea that a dying star might engulf or destroy planets is not new, but the study provides new insights into the exact process and the stage of a star's evolution where planets are most at risk. The research team surveyed a sample of more than 400,000 post-main sequence stars to determine if they could detect a decrease in the population of planets around these older planets. And this is the part most people miss... They found that gas giants orbiting close to an aged star occur at a rate of about 0.28%. For stars that have only just entered their post-main sequence phase, that rate is about 0.35%, but it drops to about 0.11% for the oldest stars in the population that have reached the red giant phase. In other words, the process of stellar aging is killing off planets. The data shows that the shorter the orbital period of a planet, the more likely it is to be destroyed. Tidal forces between the star and the gas giant cause the planet's orbit to decay, ultimately spiraling inward to its destruction. Alternatively, these tidal forces could rip gas giants apart - an equally dramatic end for these planets. Our own Sun is expected to reach its post-main sequence stage in about 5 billion years. The outlook for Earth's survival is better than for planets orbiting close in like Mercury and Venus, but it will still be a rough ride. 'Earth is certainly safer than the giant planets in our study, which are much closer to their star. But we only looked at the earliest part of the post-main sequence phase, the first one or two million years of it - the stars have a lot more evolution to go,' says co-author Vincent Van Eylen from University College London. 'Unlike the missing giant planets in our study, Earth itself might survive the Sun's red giant phase. But life on Earth probably would not.' The team hopes to improve our understanding of planetary destruction around aging stars in the future using the PLATO mission, set to launch in late 2026, whose planet-finding capabilities will allow them to examine even older stars in the red giant phase than those observed by TESS. So, what do you think? Do you agree with the study's findings? Or do you have a different interpretation? Share your thoughts in the comments below!
